1. Field of the Invention
The present invention relates to a monitoring method with a function of correlation-based system identification, especially to a monitoring method with a function of correlation-based system identification being applied to a digitally controlled DC-DC converter system for real-time monitoring frequency response of a power converter module, a digital compensator, or loop gain in the system. Moreover, a monitoring curve of the frequency response can be smoothed through an adaptive sliding window smoothing module. Therefore, data dispersion at intermediate and high frequency bands caused by non-ideal effect is effectively reduced so as to increase identifiable frequency range.
2. Description of Related Art
Along with fast development and rapid progress of digital technology, various kinds of innovative, compact and multifunctional electronic products have been developed. Thus more and more circuit modules including microprocessors, communication interfaces, and data converters etc, need to be integrated. All these modules require power converters for stably power supply. Moreover, for some high-level devices such as satellites, aerospace electronic equipment, industrial servers, etc., performance is not the only criterion to be considered. How to ensure extreme-high stability of system power supplies after long term use for good operation of the system is the most important factor.
Generally, the integrated DC-to-DC power conversion system is divided into buck converters, boost converters, and buck-boost converters according to their configuration. The main components of the converter includes four parts, a power converter for control of buck and boost, an analog-to-digital converter (ADC) for monitoring output voltages, a digital compensator for regulating stability of output voltages, and a digital pulse-width modulation module (DPWM) for control of energy output. The principle of operation of the DC-to-DC power conversion system is described as the following. The digital compensator calculates a duty cycle control (duty command) of the next cycle according to conditions of the output voltage available now. Thus the digital pulse-width modulation module outputs the duty cycle needed according to the requirements of the digital compensator. Then whether a power transistor switch of the power converter turns on is determined according to a duty cycle signal. Perform the switching repeatedly in cycles and the system generates stable direct current voltage.
Due to uncertainty of loading conditions and the power converter (such as on-resistance of the power transistor), it's difficult to design the digital compensator. Moreover, a plurality of factors including drift phenomenon of inductors and capacitors, choices of decoupling capacitors and parasitic effect has effects on the stability of the DC-to-DC power conversion system. In order to minimize negative effects of these factors and satisfy the requirement of highly integrated SoC for compact size and light weight products, a parametric system identification method for analysis of a small-signal model of the DC-to-DC power converter is revealed in some research. For modeling, the system structure must be learned firstly so as to estimate unknown parameters of the system model (such as transfer function, coefficient of state space matrix, etc). However, not all factors are taken into consideration in mathematical analysis. Especially for high-level and complicated system models, they are difficult to be constructed and analyzed. Thus frequency analysis results of the system are affected by imprecise modeling.
In order to improve the above shortcomings, a monitoring mechanism is set up in the DC-DC converter system for monitoring control loops. Moreover, users can understand conditions of the system by analyzing response of system loops and further know whether the system is stable.
Thus there is room for improvement and a need to provide a novel monitoring method of loop response of the DC-to-DC power conversion system that overcomes the above shortcomings.